Summary
Despite appearing at times to be a very good two-way wing, Prince just hasn't quite been able to get to that level on a consistent basis. He has good size for a wing and some ability to switch and guard multiple positions. Despite having good length on defense, he doesn't play to his size, and is light enough to still get bullied by bigger wings. He also has times where he simply just isn't in the right position defensively or doesn't move his feet to stay in front.

On offense, Prince has shown some brief flashes of being able to create for himself and others, but he does not have the skill level to be a go-to option. As a 37% three-point shooter on decent volume, Prince is solid there but not special.

If he can improve his defense and continue to hit outside shots at a good rate, Prince will get interest in free agency. The Timberwolves didn't fully trust Prince in the playoffs, as he only got spot minutes and got a DNP in game 6, which won't help him in free agency when teams are trying to evaluate if he can be a valuable part of a rotation.

Prince will be 28 when free agency starts, so this may be his last chance at a decent-sized long-term contract.
 
Cap Considerations
Prince will be an unrestricted free agent with a $19.5 million cap hold and full Bird rights. As his cap hold exceeds the salary he will get in free agency, and since the Timberwolves will be operating over the cap, his cap hold is not really relevant, as the Timberwolves will retain his Bird rights until he is re-signed or signs elsewhere.

If Prince demands a starting salary of more than the full $10.3 million Non-Taxpayer Mid-Level Exception, only teams with cap space will be able to sign him, unless a sign-and-trade is worked out. It's likely that Prince could be had for the full MLE or less, and would expect taxpaying teams could potentially get him with the Taxpayer MLE or less.